The valuation for the Pasadena, Calif., start-up founded by well-known entrepreneur Bill Gross (pictured here)–which was actually struck some month ago–is $40 million.

Accel’s Jim Breyer will join the board of UberMedia, maker of social media reading and posting tools, which is currently largely aimed at the Twitter ecosystem.

“We are hoping to work very closely with Twitter, which is certainly our goal, as well as other social media platforms like Facebook,” said Breyer in an interview with BoomTown this morning, answering a question about previous tensions between Twitter and UberMedia. “There will be a lot of efforts to monetize Twitter and there is no silver bullet.”

Index Ventures and Steve Case’s Revolution Ventures also participated in the round.

The company did not reveal the amount raised, nor the valuation for UberMedia.

But many like him are trying to find a way to monetize the huge microblogging platform–including Twitter–and take advantage of its enormous scale.

Armed with $3.5 million in venture funding from a group of leading investors, including Index, Revolution, betaworks, First Round Capital and angel investors such as Mahalo’s Jason Calacanis and BuzzMachine’s Jeff Jarvis.

Started in Gross’s Idealab start-up incubator and called TweetUp (and then PostUp), it was initially cast as a keyword-based bidding marketplace akin to Overture/Goto.com, the first paid search system he created a decade ago.

TweetUp also offered an organic search service to surface the best tweets. This put it at odds on several fronts with Twitter, which began to aggressively move to take over key parts of its business that had largely been left to third-party developers.

That still remains UberMedia’s essential goal, and Breyer hopes that the new investment will show Twitter that UberMedia hopes to work in harmony with it, as other developers have done successfully with Facebook. (Accel and Breyer himself are big investors in the social networking giant, so he should know.)

“Like Twitter, we want to drive the customer experience,” he said, pointing out successes such as the Zynga gaming service. “This is a lot like Facebook several years ago and cooperation worked out well for everyone.”

PASADENA, Calif.–February 14, 2011–UberMedia, the leading independent provider of applications for reading and posting to Twitter and other social media platforms, today announced that it completed a financing round led by Jim Breyer of Accel Ventures. Existing investors Steve Case of Revolution Ventures and Danny Rimer of Index Ventures also participated.

“At UberMedia, our goal is to enhance the Twitter experience with functionality in our clients and to be the best partner with Twitter in growing and enhancing their ecosystem,” said Bill Gross, Founder and CEO. “In particular, the addition of Jim Breyer to our board will really enable us to succeed at this mission. His experience on the boards of Wal-Mart, Facebook, Marvel Entertainment, Dell and so many other high-profile consumer brands will be particularly helpful.”

“We’ve been watching closely Bill’s efforts at UberMedia to build upon the ground-breaking communications platform created by Twitter,” said Jim Breyer of Accel Partners. “We see a tremendous business in the kinds of innovations in user experience being developed at UberMedia. The result of these efforts will be an expansion in the number and variety of people engaged with Twitter as well as a method for advertisers to reach consumers in highly targeted and relevant ways.”